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Native Trees of Prince Edward IslandThe Birches
Background:
The four birches native to Prince Edward Island range from the common to the very rare. As with other families, each member has a distinct place in our Island ecosystem, though there may be two or even three species growing in the same area. Each has its own tolerance for sun and moisture. Growth rates, life span and wood quality also differ widely.
Yellow (Betula alleghaniensis), White (Betula papyrifera), Grey (Betula populifolia), Bog (Betula pumila)
Birch leaves. From left, white, grey and yellow birch.
Identification:
All birches have toothed leaves that are simple and alternate. When young, it is difficult to distinguish species by bark, since they all have reddish-brown, shiny bark with white spots (lenticels). Yellow birch can grow to be one of our largest deciduous trees, reaching a height of 21 m (70 ft) and up to .9 m (3 ft) in diameter. The bark of older yellow birches is a golden yellow and tends to shred rather than peel in large blocks. If the bark of yellow birch twigs is scraped, it produces a strong scent of wintergreen. Once it is six or seven years old, white or paper birch is most easily recognized by its brilliant white, peeling bark. Grey birch also has white bark, though it peels very little and has distinct black marks under each branch. It is also called wire birch, due to the large number of fine branches. As you might expect, bog birch is a small tree, rather more like a shrub. It rarely grows more than 3 m (10 ft.) high and on all specimens I have encountered the bark remains like that of any juvenile birch.
Yellow birch
Habitat:
Yellow birch is the longest lived of our native birches and is quite tolerant of shade. These characteristics made it a strong component of our Acadian forest, especially on the upland hardwood sites. While it grows well in moist conditions, such as alongside streams, it does poorly where there is standing water. It is often found growing in association with eastern hemlock, red and sugar maple and white pine. White birch is an early successional tree, growing on dry, exposed sites, including burned areas. It grows poorly in shade, and is often associated with poplar, pin cherry and balsam fir. Grey birch can often be found with white birch and its associated species, again on dry sites, while bog birch lives up to its name, being found in acidic, boggy areas. It needs full sun to thrive and is usually surrounded by plants with similar tolerances - willow, rose, Labrador tea, larch and black spruce.
Yellow birch bark.
Propagation:
Birch seed is grouped in cone-like strobiles and can be collected by hand from shorter trees. Pick when the strobiles are fully developed and break apart quite readily. On taller trees, it is often possible to find strobiles under trees after a strong windstorm. Birch seed is easy to clean. Simply rub the strobiles over a screen or strainer that will allow the seed to drop through and catch the bracts. Seeds need a cold period before planting, so they can be stored in a fridge with a small amount of damp peat or potting soil. In the spring, sprinkle the mixture on top of a seedbed, but do not cover with soil. Birch seed needs light for germination but doesn't like to dry out. A slatted table (providing 50% shade) and regular light mistings provide optimal conditions for germination. My one attempt with bog birch was unsuccessful, probably due to an insufficient cold period, but I will be trying again to reproduce this rare plant.
White birch bark.
Wildlife uses:
Birch seed is an important food source for many winter birds, including American goldfinch, pine siskin, northern junco, blue jay, and the chickadees and sparrows. Birches regularly produce heavy crops of seed and larger trees can be quite important to local populations of birds. During the Christmas bird counts, especially if the surface of the snow is crusty, you can see dozens of small birds chasing after birch seed that has been scattered by the wind. While the seed is important for wildlife (including small mammals), the trees are used in many other ways. Ruffed grouse can often be found in birch trees during the winter eating the buds, and snowshoe hares browse the twigs. In spring, birch flowers attract many insects, which in turn attract large numbers of migrating warblers.
White birch leaf.
Birches can also be important nesting sites for red-tailed hawks and vireos, as well as cavity nesting birds such as chickadees and woodpeckers. Small strands of birch bark are the key materials used by vireos in their hanging nests, while many other birds and red squirrels incorporate this material into the nest and den linings. In addition, yellow-bellied sapsuckers regularly drill into birches to allow sap to run out and attract ants. As you can see just from this partial list of wildlife uses, the birches are important to a wide variety of species.
Grey birch bark.
Conservation:
White and grey birch are two of our most common hardwoods and need very little help in the form of conservation. While important trees, they do very well in clearcuts and disturbed sites, as long as the soil is dry, so we are fortunate to still have large populations. This doesn't mean that we should discriminate against them they are still excellent trees to plant in windbreaks and around homes, as well as when restoring severely degraded sites.
Grey birch leaf.
The other two species of birch are another story. Yellow birch is still relatively common in the upland hardwood areas of the province, but these types of forest are becoming rare in all but the younger age classes. Large, high quality yellow birch are not common. Since it is such an important component of the Acadian forest, we need to continue efforts to protect and encourage this species. Yellow birch is one of the key species we use at Macphail Woods to restore degraded woodlands. We have planted them (with a variety of other appropriate species) in small patch cuts made in old field white spruce and in both hardwood and softwood thinnings. We have also used them to add value and diversity to conifer plantations once those trees are providing some shade.
Bog birch is one of our rarest plants and all efforts should be made to conserve this species. Many of the bogs where it may have historically been found have suffered serious habitat disturbance. It can still be found on the remnants of the Miscouche bog and a few other areas and these sites should be protected from further development. It is not inconceivable to see this species being extirpated from the province without strong government intervention.
For more pictures and descriptions of this species, check out the Atlantic Forestry Centre, and the
Iowa State University Dendrology page and the Dendrology at Virginia Tech Page and the Virtual Foliage Homepage. For a review of the ecology of this species, refer to the Silvics of North America.
In 1806, John Stewart wrote an excellent description of Forest Trees and Other Vegetable Productions on PEI at that time.
Read more here.
We offer a number of workshops and guided tours at the Macphail Woods and it is an excellent opportunity to learn more about the native trees of Prince Edward Island. Check out the Events Calendar for more information. Web development and maintenance by Chris Martin.
